U.S. Pat. No. 4,179,580 (Cobb), European Pat. No. 128001 (Kudoh et al.), and Eberhardt et al., Journal of Organic Chemistry, Vol. 30, pp. 82-84 (1965) show that it is known that supported alkali metals are useful as catalysts in the coupling of ethylenically-unsaturated hydrocarbons with aromatic hydrocarbons having an active hydrogen on a saturated .alpha.-carbon. The supported alkali metals are more effective than the corresponding unsupported alkali metals in such reactions but are still not as effective as might be desired.
As disclosed in copending applications Ser. No. 135,318 (Smith), filed Dec. 21, 1987, now abandoned, and 276,531 (Smith), 276,532 (Smith), and 276,533 (Smith), filed Nov. 28, 1988, now abandoned, it has been found that alkenes can advantageously be coupled with aromatic hydrocarbons having an active hydrogen on a saturated .alpha.-carbon in the presence of a supported alkali metal as a catalyst and about 10-100 mol %, based on the amount of the alkali metal catalyst, of an oxide of sodium, potassium, rubidium, cesium, barium, strontium, calcium, or magnesium as a co-catalyst. However, it has also been found that inferior results are obtained when the catalyst system is prepared in the conventional manner, i.e., by dispersing the alkali metal onto a mixture of the support and the oxide in the presence of a diluent.